Motor-driven dual pumping unit



inventor: FrankARose krah ls Akhorney.

F. A. ROSENKRANS MOTOR-DRIVEN DUAL PUMPING UNIT Filed Sept 28, 1949 June 30, 1953 Patented June 30, 1953 U N I T ED .S TATES PATENT. O F F ICE MOTOR-DRIVEN DUAL PUMPING UNIT Frank A. Rosenkrans, BridgeporhC onn assignor to General Electric Company, a corporation of New York .6 Claims.

This invention relates to an improved pumping unit in which one of a pair of pumps may be selectively operated, and particularly relates to an improved clutching arrangement by which one or the other pump may be drivingly engaged according to the direction of rotation of a drive shaft common thereto.

The objects of my invention are to providean improved, simplified, clutching arrangement for driving one of a pair of conventional impeller pumps from a common reversible drive shaft; to provide a pumping device having a pair of pumps driven from a common drive shaft with clutch devices individual to the pump and respectively automatically engageable and disengageable asa result of reversing the rotation of the drive shaft; and to provide a simplified dual pumping means for an automatic washing machine or the like in which control of the operation of the respective pumps may comprise a "conventional reversing switch in circuit with the pump drive motor.

I accomplish these objects in a presently preferred embodiment of my invention by fixing a reversible drive motor between the respective pump structures and providing a novel combination of rotor and drive shaft comprising a threaded drive shaft freely operable within a cooperatively threaded rotor core. The ends of the drive shaft project into clutch casings in dividual to the pumps and carry clutch elements for cooperation with clutch members drivingly affixed to the pump impellers. The inertia of the drive shaft at the instant the motor changes its direction of rotation will cause a translation of said shaft axially within the rotor to disengage one clutch and engage the other. The pumps may therefore be selectively operated merely by appropriate direction of rotation of the motor.

In the accompanying drawings Fig. 1 is a representation of a conventional automatic Washing machine embodying the dual pump disclosed herein, and Fig. 2 is a side elevation, partly in section, showing a presently preferred embodiment of my invention.

I have chosen to illustrate my invention as applied to an automatic washing machine of the type shown in Fig. 1. The washing machine includes a tub having a side Wall I and a bottom U "the clothes or for spinning-the 'tub'fi for removiinglthe water therefrom, according to the program established .by conventional time-cycle means (not shown). In the type of machine illustrated the clothes are placed within the basket :5 and by suitable automatic controls, Water'is introduced into=the tub I and is-pumped therefrom into the basket. Overflow from the basket operates a float valve (not shown) to shut off the 'incoming'watersup-ply, and thenceforth during the washing operation water is continually circulated from the tub through a conduit 1 andspout :8'into the basket from which it returns again to the tub. The advantage of such circulation derives from the facility with which lint and the reaction products of soap may he continuously filtered from the water by .an annular screen ;9 on to :which the water discharges from the spout 8. The tub 6 is emptied by spinning, whereupon "the water flows through the plurality of openings It and returns to the tub, from which it may be discharged to a sewer connection. 'It will be understood that during the evacuation of water from the tub the circulation therefrom to the basket .6 must be discon- 'tinued. Previously it has been the practice to employtwo individual motor driven pump units, respectively for circulation "and draining.

"The present invention'aifords means whereby :a single composite unit I 2 will efficiently perform these functions without conflict; and .pursuant to the :invention, a conventional reversible motor i4 drives the respective draining and recirculation pumps continuously.

Referring now to Fig. 2, each :of the pumps 'comprises'a housing ll having a wall l8 which divides the housing into a pump chamber 119 and a clutch chamber 29. The housing issubstantia'lly cylindrical except for the conventional .involute form of the pump chamber and the appropriate outlet-connection -:2i. The pump intake maybe integral :with a cap 22, and may advantageously have arfianged end, as shown, for attachment to the .tub bottom. Wall l8 providesiaibearing surface and stumngboxmounting for a shaft 23, -.to one end of which is affixed an impeller -24 and to the opposite end, a clutch -element 25. It will be understood that the-housing and equipment of the respective pumps l5 and 1'6 are identical except for appropriate arrangement of the impeller blades and orientationof the involute pump housing, and identical reference characters have been applied thereto.

The motor 14 may conveniently be mounted relative to the pumps by clamping the stator of said motor within pockets provided by 'theilanges 26 of the pump units, draw bolts or equivalent being used to integrate the assembly. Carried by a shoulder in each of the flange structures 26 is a bearing mount 2i within which is tightly affixed the bearing units 7:8 which journal he rotor 30. To this end, the rotor may advantageously be provided with the collars which engages the inner ball race member with a tight fit. It will be understood that ball bearings are illustrative only; any suitable anti-friction bear ing, which combines its normal function with that of restraining the rotor against axial movement within the pinup assembly may be used.

The operation of the respective pump clutches derives from utilising the inertia forces of a relatively heavy drive shaft and clutch arrangement so that at the instant the motor changes direc tion the drive shaft will lag behind the rotation and be cammed or otherwise driven into an axial shift according to the direction of rotation. I have found that a convenient means of accomplishing this is to provide a drive shaft 32 having its central portion arranged for freely fitting cooperation with a threaded combination cam and drive sleeve 33 comprising the core of the rotor. The representation of the threading in Fig. 2 is not intended to identify any partic ular type. The threading on shaft 32 may be continuous or intermittent, may be turned on the shaft itself, or may comprise a threaded sleeve or equivalent carried thereby. A suitable shaft screw is a three thread Acme, pitch. Where compactness is not a factor of importance, threaded elements may be affixed to the ends of the rotor for cooperation with appropriately threaded portions on the shaft; in such arrangement the axial aperture through the rotor would be of larger diameter than. the shaft. Drive shaft 32 extends through suitable bearings 34 carried in walls 34a forming the end closures of the respective clutch housings. The bearings 34 are such as to permit free axial movement of the shaft 312 thcrethrough. An oilite type of material is suitable for sleeve 33 and bearings 34. At each end the drive shaft carries a clutch element 35. A simple cone clutch has been illu trated, and is suitable for moderate loads and light mating pressures. I prefer to provide cushioned stop means to prevent jamming of the shaft in the rotor, and therefore thread the shaft with a suitable machine thread at the opposite ends of the sleeve 33 for securement of a screw threaded backing plate 36 having a resilient facing or cushion surface 37!. Said surface may advantageously be of oil resistant rubber substitutes.

In Fig. 2 it will be noted that the shaft has been driven to the right so that the respective clutch elements are in engagement for operation of the drain pump l5. As indicated by the pitch of the drive thread on the shaft 32 this requires a clockwise rotation of the motor as viewed from the right end of Fig. 2. Ihe shaft 22 has progrossed axially to the right until the cushion surface 31 at the left portion of said shaft has engaged with the flanged end of the sleeve 33 and has become slightly compressed. In such position the respective right-hand clutch members are maintained in resilient engagement at moderate pressures. Assuming now that a draining operation has been completed and the circulating pump I6 is to be operated (as would occur in an automatic washing machine as the operation progressed from a presoak to wash stage of operation) the automatic timing means would 4. operate the motor switch to reverse the motor direction. The inertia of the shaft and its associated clutch elements, plus the resistance to reverse rotation presented by the respective pump impellers, would contrive to hold the drive shaft assembly stationary at the commencement of reverse rotation of the motor, whereupon the camming effect of the relatively freely fitting rotor threading and drive shaft threading initiates axial movement of the drive shaft to the left of Fig. 2. Even after the shaft begins to rotate, it will lag behind the rapidly rotating rotor and therefore continue its axial movement. Accordingly the shifting shaft will almost immediately disengage the right-hand drive clutch and thereafter bring the left-hand clutch elements into engagement to drive the pump associated therewith. The drive shaft movement will be aided in some measure by the expansion of the left-hand cushion member 37. The continued axial thrust of the motor caused by the pumping load maintains clutch engagement pressure during the driving period.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made; and I therefore contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a pair of friction clutches having axially separated clutch members, a drive shaft common to said clutch members and connected thereto to effect clutching or declutching of said members upon axial shift of said drive shaft in one or another direction, and means for shifting said shaft and driving the same to transmit torque to said clutch members, comprising a helical screw secured about said shaft, a threaded sleeve cooperative with the threaded portion of said shaft and carried by the threaded portion of said shaft, bearing means for mounting said sleeve for rotation while restraining displacement axially of said shaft, and motor means for reversibly rotating said sleeve.

2. In combination, a pair of friction clutches, a drive shaft common thereto, bearing means journaling said shaft while permitting axial movement thereof, means whereby movement of said shaft axially relative thereto engages or disengages at least one of said clutches according to the direction of shaft movement, and means both for axially shifting said shaft and driving the same to transmit torque to said clutches, and means comprising a helical screw secured on said shaft, a cooperatively threaded sleeve on said helical screw, means for mounting the sleeve for rotation while restraining axial displacement thereof relative to said shaft and means for reversibly rotating said sleeve.

3. In combination, a pair of clutches having axially separable clutch members, a drive shaft common thereto, means whereby axial movement of said shaft effects engagement of one clutch and disengagement of the other according to the direction of axial movement, and means both for shifting said shaft axially and driving the same to transmit motor torque to said clutch members, said means comprising a helically threaded portion secured on said shaft and a cooperatively threaded axial core member on said shaft threaded portion, said core member being fixed within the rotor of a reversible drive motor disposed about said shaft, and said rotor being mounted to preclude axial movement relative to said shaft.

4. A dual pumping unit comprising a pair of pumps designed to pump at respectively different directions of rotation, a clutch device individual to each pump and having clutch elements engageable or disengageable by appropriate axial movement of one of said elements relative to the other, a drive shaft common to said clutch devices, said shaft having a helically threaded portion disposed intermediate its end, and a reversible motor having a stator fixed relative to said shaft and a rotor carried by said shaft, said rotor being cooperatively threaded having a relatively free fit with said shaft threading and mounted to preclude axial movement relative to said drive shaft, whereby the rotor imparts an axial thrust to said shaft.

5. A dual pumping unit comprising a pair of pumps designed to pump at respectively different directions of rotation, a clutch device individual to each pump and having clutch elements engageable or disengageable by appropriate axial movement of one element relative to the other, a drive shaft having aflixed to its respective ends the said axially movable clutch elements, said shaft having a threaded portion intermediate its ends, and a reversible motor fixedly secured between said pumps and having a rotor mounted on said shaft and supported to preclude axial movement relative thereto, said rotor having a screwthreaded core fitting freely on said threaded shaft to impart an axial thrust to said shaft.

6. A dual pumping unit comprising a pair of housings, each housing having a pump chamber and a clutch chamber, an impeller in each pump chamber and a clutch means in each clutch chamber, each of said clutch means having an element drivingly connected to its respective impeller and a second element engageable or disengageable with said first-named element upon axial movement relative thereto, a drive shaft having affixed to its respective ends the secondnamed clutch elements, means for journaling said drive shaft While permitting axial movement thereof, a reversible motor having a stator clamped between said housings for support thereby and having a rotor disposed about said shaft and mounted to prevent axial movement relative thereto, said rotor being connected in relatively free screw-threaded relation to said shaft to exert an axial thrust on said shaft according to the direction of rotation of said motor to thereby drive one of said shaft-afiixed clutch elements into torque transmitting contact with its associated element, and resilient means carried on said shaft for resilient engagement with the rotor prior to the engagement of said lastnamed clutch elements.

FRANK A. ROSENKRANS.

526,780 Germany June 10, 1931 

